Track driven machines with torsion bar-activated controls

ABSTRACT

Track driven machines useful in slip form and other road paving operations embodying a support frame supported by hydraulic cylinders on a pair of power driven, endless tracks. The frame is maintained in a pre-oriented plane as the machine moves along terrain by a hydraulic fluid control system operating cylinders in response to torsion bar-registered twist of the frame, stringline feeler means and a level controller.

United States Patent [1 1 Dale [ TRACK DRIVEN MACHINES WITH TORSION BAR-ACTIVATED CONTROLS [75] inventor: Charles Harry Dale, Rock Island, 111.

[73] Assignee: Pav-Saver Corporation, Moline, 111.

[22] Filed: Apr. 17, 1974 [21] Appl. No.: 461,633

[52] US. Cl 404/84; 280/6 R; 180/41 [51] Int. Cl. E01C 19/00; FOlN 1/00 [58] Field of Search 404/84, 83; 280/6 R, 6.1; 180/41 [56] References Cited UNITED STATES PATENTS 3,257,917 6/1966 Lewis 280/6.8

3,264,958 8/1966 Babb et al 404/84 3,296,722 1967 Gurlett 280/6 R 51 Sept. 16, 1975 3,691,916 9/1972 Martenson et al 404/84 3,782,844 l/l974 Burgin 404/84 Primary Examiner-Mervin Stein Assistant Examiner-Steven Hawkins Attorney, Agent, or Firm-Johnston, Keil, Thompson & Shurtleff 1 ABSTRACT Track driven machines useful in slip form and other road paving operations embodying a support frame supported by hydraulic cylinders on a pair of power driven, endless tracks. The frame is maintained in a pre-oriented plane as the machine moves along terrain by a hydraulic fluid control system operating cylinders in response to torsion bar-registered twist of the frame, string-line feeler means and a level controller.

6 Claims, 12 Drawing Figures PATENTED SEP I 61975 SEIIET 3 BF 4 PATENTED SEP 1 61875 sum 4 UF 4 FIG. IO 24 TRACK DRIVENMACHINES WITH TORSION BAR-ACTIVATED CONTROLS The invention herein pertains totra'ck "driven machines in which a support frame is moved along terrain by a pair of power driven, endless, tracks mounted on respective sides'of the frame. The track support structures are connected to the respective sides of the frame by mechanical coupling meanskeeping the frame and tracks together while allowing vertical movement of the frame relative to the tracks. At least one comer of the frame is suspended on a track by a hydraulic cylinder. Preferably there are two hydraulic cylinder members on each side of the frame a total of four cylinder members in a quadrant arrangement each supporting its adjacent part of the frame. The four cylinders constitute the sol'e, or at least the'principal, means of support of the weight of the frame on the two tracks. The hydraulic cylinder mounting on the frame allows the frame to float through a predetermined path irrespective of up and down movement of the tracks as they pass over irregular terrain. I

The floating effect for the frame isachieved by utilization of hydraulic fluid pressufizing means connected by hydraulic fluid lines to respective hydraulic cylinder members in combination with electro-hydraulic fluid control means operatively associated with a'torsion bar which is rigidly connected atone end thereof to the frame, string line feelers, and preferably also a slope control unit. The torsion bar'is'adapted to register twisting forces in the frame means as the machine moves along irregular terrain. Such twisting forces occur when one track begins to" rise or fall relative to the other track. At this point, the torsion bar-registered twisting of the frame is translated by a mechanical linkage to aswitch in the electro-hydraulic fluid control means-The latter operates a hydraulic cylinder to raise or lower a corner or segment of the frame'in the direction torelieve the twisting forces therein. V

' "Thus, as the machine moves along irregular terrain, the torsion bar-hydraulic fluid controlsystem maintains the frame in an essentially twistforce-fre'e condition by moving one segment or corner of'the'frarne up or down in a twist -fo'r'ce-relievin g' direction. 4

The invention further provides in the hydraulic control system other controls which may be used to operate the remaining hydraulic fluid cylinders. Preferably the torsion bar-registered twist in the frame is used to operate'only one of the four cylinders. The other cylinder on the same side of the machine may also operate in response to torsion-bar registered twist, but preferably this cylinder is activated by a hydraulic fluid control means operatively associated with another type of control which maintains a predetermined position or elevation of one side of the frame relative to the other side of the frame. Suclf'a control expediently, particularly in road paving machines having means mounted on the frame for spreadingand laying a strip of road paving machine on a roadbed surface, is an adjustable or'fixed level control which is responsive to the angle of the horizontal plane of the frame relative to true horizontal. This control canbe preset at zero or any indicated small angle relative to true horizontal so that the cylinder controlled thereby will raise or lower its side of the frame relative to the'opposite side of the frame to maintain the desired horizontal orientation of the frame relative to true horizontal.

The weight distribution on theopposite side of the frameis supported on its'track; either wliolly or partially, by' two additional hydraulic cylinder members spaced axially along the track in amanherproviding' a substantially quadrant arrangement in the four cylinders. In lesser refined forms of the invention, such hydraulic cylinder support for the opposite side of the frame may be dispensed with in favor of rigidconnectionof the opposite'side of the'frame to its' track, augmented by partial or replaced by springsupported'suspension of the opposite side, and the like. t

In more refined forms of the invention", however, and particularly in 'the machines used for road paving and- /or other road building purposes, the opposite sideof the frai'ne is supportedas aforesaid by two additional hydraulic cylinder members. These cylinder members are articulated, either jointly or severally, by one or two elevation control means 4 an embodiment "of which are string-line feelers having horizontal arms which follow a string line set' at predeterminedelevations along the side of the roadway being laidJThese string-line feelers activate a further hydraulic control system to cause the opposite side of the frame to move in a path corresponding to the elevations of the string line and independently of actual up anddown movement of' the corresponding track as it travels along the road bed sur face or the terrain adjacent thereto. a

The combinationof the four hydraulic "cylinders and their controls as aforede scribed keepthe frame of a road paving machine in a predetermined horizontal plane and atpredetermined elevations as the paving r'nachine moves forwardly along aroadb'ed'. One form of paving machine for which the subject invention is particularly adaptable'is a slip formp'avingmachine which operates 'off a'string line and lays "road'paving material, e.g., low slump concrete, without the need for prelaying of formsalong the road bed-surfaceilhe frame of the slip form paving machine in turn supports one or more members which spread, compact, smooth, and/or finish the wet concrete into a strip of predetermined thickness, elevation and/or slope. For example, the frame may have supported thereon a' transversely extending auger or au'gers which rough-spread piles of concrete dumped on the road bed. Such auger or augers normally project forwardly'from the main frameof the machine. Following the auger unit, there may be 'a series of transversely spaced vibrators which extend into the wet concrete to impartthereto a compacting and/or settling effect. Another concrete working device supported by the main frame of the machine, either directly orindirectly, is a tamping barwhich reciprocates vertically into the rough-spread wet concrete to further compact it into a layer or substantially'uniform composition and/or work heavier aggregate near the surface of the layer'rhore deeply into the layer.

A further concrete working member is a strike-off plate or member having a lower edge or surface adapted to shape the upper surface of the rough-spread concrete into 'theactual or approximate plane of the road surface such plane having either a fla't configuration of a crowned configuration. 1

All of these concrete working unitso'r members operate between a pair of slip forms respectively mounted near to and parallel with the tracks of the machine. These slip forms principally comprise horizontally elongated plates or other flat surfaces lying in respective vertical planes. As the other parts of the machine work the concrete and shape its upper surface, the slip forms retain the concrete in the lateral direction of spread and ultimately shape the sides of the finished concrete strip left behindthe machine as it progresses along the road bed.

,The ultimate shape, elevation, and horizontal orientation of the upper surface of the finished concrete strip is determined principally by the positions assumed by a horizontal finishing pan or sheet, herein called a crown pan, and vertical slip form plates attached to opposite sides of the crown pan and depending therefrom. The pan in turn is supported by and below the floating, frame of the machine. The longitudinal direction for the finished concrete strip is determined principally by the path taken bythe two tracks Control of the track drives may be done manually, but preferably is done off the same string line by a string-line feeler having a vertical-arm which lies against the string line. Thus a machineis capable of operating almost automatically offa string line in the laying of a roadway strip having the designed vertical elevations and longitudinal path vpreviously laid out by the string line extending along one side of the projected road bed. When such string lines are laid out by surveying instruments, precision rough-grading and/or finished grading of the roadway bed is of lesser criticality than in cases where other pavement laying techniques are used, e.g., formpaving between prelaid pavement-forming rails or plates. Even with relatively irregular rough-grading, the tracks of the machines of the invention can move over the relatively rough grading .without adverse effect upon the ultimate actual elevation, shape or direction of the roadway which is laid.

A further advantage of the machines of the invention embodying the aforesaid hydraulic cylinder support of the frame on the tracks and the torsion bar-actuated control system, with or without the slope control system and/or the string-line control system, is the ability to drive the machine over rough, ungraded terrain, ditches, or other terrain irregularities.

In trucking road paving machines to and from the road sites the machines are often loaded or unloaded at points remote from the road bed and must move under their own power between the truck and road bed. Similarly, the machines may be called upon to move under their own power on non'road bed terrain either for parking purposes or changing sites along the road bed. In such movements, the machine encounters irregular terrain, ditches, etc. which it must move across without loss of track traction, tipping, excess strain on the machine frame, etc. The machines of the invention allow the two tracks to pivot in a vertical plane relativeto the frame and independently of each other, the extremes of which are orientations with one track sloping downwardly and the other sloping upwardly due to terrain conditions. Even such orientations do not impart excess twist strains to the frame of the machine because of the intermediary support of the frame by the torsion bar-controlled hydraulic cylinder, whose extension and/or retraction responds to the orientation of the individual tracks and keeps the frame in a relatively stable plane substantially free of excess twist strain.

The aforesaid features and advantages of the invention may be realized by the preferred embodimentof FIG. 1 is a top plan view of a slip form paving machine;

FIG. 2 is a rear elevation of the machine;

FIG. 3 is a diagrammatic side elevation of the machine, partially in full lines andpartially diagramatic;

7 FIG. 4 is a fragmentary, top plan view of a segment of one track of the machine and the appurtenant segment of the frame;

FIG. 5 is a fragmentary, side elevation as viewed from plane 5-5 of FIG. 4; v I

FIG. 6 is a fragmentary side elevation as viewed from section 6-6 of FIG. 4;

FIG. 7 is a fragmentary top plan view of the torsion bar of the machine, the arm mounted on the torsion bar, and the arm of a hydraulic control system moved by the first-mentioned bar;

FIG. 8 is a rear elevation of the assembly illustrated in FIG. 7 as viewed from section 8-8 of FIG. 7;

FIG. 9 is a side elevation, in fragment, of the assembly illustrated in FIG. 7 as viewed from section 9-9 of FIG. 8;

FIG. 10 is a phantom top plan view of the paving machine and a semi-diagrammatic illustration of the hydraulic system of the machine and the electrical controls thereof;

FIG. 11 is a fragmentary, phantom, rear plan view of the machine showing also the hydraulic system and part of the electrical control of the machine; and

FIG. 12 is a side elevation of the frame and connecting structure for joining the frame to a track.

Referring to the drawings, the preferred embodiment of the invention is a slip form paving machine 20. It has a first endless track means 22 and a second endless track means 24 extending along and projecting forwardly and rearwardly beyond opposite sides of the main frame 26 of the machines. The first track means 22 and the main frame 26 are connected by hydraulic cylinder members 28 and 30, which members elongate and contract in the vertical direction. The second track means 24 is connected with the opposite side of the frame 26 by similar hydraulic members 32 and 34.

the main support frame 26 for the machine comprises a first side rectangular tube 40 and a second side rectangular tube 42; a front cross frame member and a rear cross frame member 46. These beams may be of any constructing meeting the requisite strength requirements, e.g., l-beams, heavy plates, angle irons, cylindrical or rectangular tubes, or composites thereof.

The main support frame 26 carries the power and drive components and the concrete working components of the machine. Referring to FIGS. 1 and 2, these components include a combustion engine powered power plant, i.e., the diesel driven power plate 62; a direct current generator 60; a control console 64; an operator platform 66; an electro-hydraulic control unit 68 with a hinge cover 67, which control unit is mounted on the hydraulic fluid reservoir 69.

The concrete working and finishing components of the machine are also supported on the main frame or, in some cases, by the frame structure for the track means 22 and 24. The concrete working components include a spreading auger 70 located forwardly of the main frame 26 and preferably between the track means 22 and 24. This auger is composed of two independently driven sections, each having a helical flight 72 and 74 of the same or opposite hand. The helical flights are mounted on hub tubes 76 and 78, which in turn are rotatably driven separately by the split shaft 80. This shaft is supported in the center bearing 82 and also in the chain sprocketunits 84 and 86. The chain sprocket units 84 and 86 rotatably drive their respective halves of the split shaft 80 "and the auger unit connected thereon in either direction of rotation, the rotatable drive of, each auger section being provided by the hydraulic motors 88 operatively connected to the chain sprocket units. The function* of the auger -70 is to spread piles of concrete dumped on the roadbed site substantially evenly across the road bed to be laid as the machine advances along the road bed. The hydraulic motors are reversible and are driven by hydraulic fluid supplied through hoses or pipes (not shown) connected to the hydraulic fluid'pump reservoir. The direction of flow'of the hydraulic fluid and hence the direction of rotation of hydraulic motors 88 is controlled in the known and conventional manner by valves operated by two of themanual levers 73 'on the control console 64.

Immediately following the auger 70 is a horizontally elongated, vertical strike off plate 90 fixedly or adjustably connected .to and extending between the chain sprocket units 84 and,86. This strike off plate levels off the wet concrete spread by the auger 70 at the depth desired, the excess concrete piling up against. the face of the strike off plate 90. The strike off plate 90 levels the slap of wet concrete at a rough depth sufficient to provide the ultimate desired thickness or elevation of the upper surface of the concrete strip being laid.

Both the auger 70 and the strike off plate 90 are supported by forwardly extending arms 92 and 94, which in turnare pivotally supported by stub shafts 96 and 98 on the frame structures (hereinafter described) for the track means 22 and 24. Suitable hydraulic or mechanical articulation means (not shown) may be used to pivot arms 92 and 94 for raising or lowering the auger 70 and strike off plate 90. V j I As the machine travels forwardly, the auger 70 and strike off plate leave behind a slab of wet concrete which needs to be further worked to provide the requisite concrete properties, finish and shape for the roadway. The main frame 26 has supported thereon between it and the strike off plate 90 a ganged vibrator unit 110 comprising a horizontal bar or beam 112 extending between arms 92 and 94. The beam or bar 1 12 has supported thereon at regularly spaced intervals a plurality of electrically powered concrete vibrators 114, the horizontal, lower ends of which dip into and travel through the wet concrete slab to work the concrete and its aggregate. The vibrators are each connected to the coupler boxes 116, which have electrical connectors or couplers 118 for the wire connection between the coupler boxes and the vibrators 114.

Thebar 112 may further have supported thereon plates 120 and 122. Such plates may be heavy gauge sheet metal oriented in the vertical plane and having a size sufficient to function as fins or baffles. Such fins or baffles preferably are located about midway between the vibrators 114. 1 I

The ganged vibratorunit llO is coupled to the frame by hydraulic cylinder articulating units 124 and 126. The hydraulic cylinder members raise and lower the vibrators 114 and the bar 112, the bar 112 being supported by any expedient mechanism.

A tamper bar 128 extends laterally across the front of the frame 26. It is reciprocated into and out of the A crown pan' (FIG. 2) lies beneath the frame 26.

This crown pan functions to level and smooth the strip of wet concrete in the configuration desired. The crown pan is mounted by mechanism shown in my US.

Pat. No. 3 377,933 disclosure of which is incorporated herein by reference, so that it can be set at the desired elevation and provided with an arch or crown, if desired.

The rear plate 152 attached to the frame member 46 has mounted thereon solenoid valve units 154 and 156, such units being a part of the hydraulic system herein after described. I

A torsion bar (FIG. 1 and FIGS. 7-9) extends from front to rear of the frame 26. The front end of the torsion bar 160 is rigidly secured to the frame tube 44 by an angle iron or bracket'memb'er 162. The torsion bar comprises a tube 166 rigidly'secured to the member 162 and a rod 168. One end 170 of rod 168 is fixedly secured-in the end of the tube 166. The rod 168' is piv- 'otally supported in thebearing or sleeve 164, which is mounted on the frame tube 46 by .the angle-iron bracket 172.

Thetube remote end of the rod 168 projectsslightly' rearwardly of the frame tube-48. A vertical ami is mounted by clamp 174on the projecting end of the rod 168. A plate 176 is bolted to vertical arm 175,anda horizontal elongated bar orarm lj 78'is bolted to plate 176. When the torsion bar 160 is twisted clockwise or counterclockwise in response'to twist of the frame 26, thearm or bar 178 is pivoted in a vertical pla nei The torsion bar-remote end of the bar or arm moves either up or down. If desired, a vertical guide rod 180 on an arm 182 may be mounted on the rear frame member 46. The guide rod 180 extends through 'anapertured guide plate 184 in a manner allowing free pivotal'movment of the arm 178 by preventing excessive frorit to rear displacement of arm 178. i

A bracket 186' is mounted'on the free end of the arm 178. It carries a vertical thumbscrew 188 which may be adjusted vertically. 'The lower end of the thumbscrew bears on a strike bar 190 secured to one end of the pivot arm 192. The pivot arm 192'is supported by shaft 194 in a'housing 198 of an electrical sensor'unit. Such units are commercially available and are known in the art. The arm 194 may have counterweights 196 and/or may be spring loaded to urge arm 192 to rotate in the clockwise direction as viewed in FIG. 8.

The sensor unit has in the housing198'electrical switch means (not shown) which sense pivotal movement of the arm 192-and shaft 194 in either the clockwise or counterclockwise direction. The sensor unit is The front frame tube 44 carries a front strike plate 200 (FIG. 9) against which the wet concrete accumulates just prior to the smoothing and shaping of the concrete beneath the crown pan. The tamper bar 128 works the concrete just ahead of and slightly below the strike .plate 200. Details of the strike plate and the crown pan structure are described in my aforesaid U.S.

patent.

Each track means 22 and 24 comprises a track frame 210 (FIGS. 36). Such track frame comprises a pair of elongated, horizontal, heavy frame plates 212 and 214. These plates in turn are rigidly connected to a pivot bearing 216, which rotatably journals a shaft 218 extending from the bearing 216 toward and beyond the side frame tube 42,

The shaft- 218 is connected to an arm 220 which is pivotable relative to the shaft. The arm 220 extends horizontally beneath the frame tube 42 in a rearward direction. toafrear pivot bearing 221, hereinafter described.v v

The lower end of the, hydraulic cylinder 224 of the front hydraulic cylinder members 28 and 32 are mounted by frame or bracket members 222 attached to the arm .220., Thus, the lower end of these hydraulic cylinders have rigid interconnection with the arm 220 and also the respective track means 22 and 24. The upwardly extending piston rod 226 of each hydraulic cylinderis connected by pivot joint 228 to a bracket 232 .rigid ly connected by brace plate 230 to the forward end ;rear ends thereof by a 'slide bearing 236 to the sides of the frame 26. This track bearing allows the frame 26 to move up and down relative to the tracks but restrains the tracks from separating from the frame in a lateral direction. Referring to FIGS. 4-6, the slide bearing 236 comprises vertical channels 238 and 240 mounted on the plate 242 to form a vertical channel structure. The plate 244 is bolted to each track frame 210. A T-bar 246 is rigidly attached to the arm 220 and matingly fits in the channel to form the slide bearing. Such bearing has a minor amount of lateral play tolpermit the frame 26 to move relatively freely in a vertical direction relative to each of the track members.

Referring to FIG. 12, the frame 26 and the components mounted thereon are drawn forwardly by the trackmeans 22 and 24 via the arm 220. The front end of the arm .220 is connected to each track means via the bearing 216 which is rigidly connected to the track means. The rear end of the arm 220 is connected to the rear cross frame 46, 152 by the bearing 221, which is rigidly mounted on the rear plate 152 and pivotally connected to the rear end of the arm 220. A vertical bar 223 is fittedly attached to the side frame 242 and extends downwardly along the outer side of the arm 220. This restrains the forward end of the arm 220 and aids in keeping the respective track means from draw ing away from the frame 42. It relieves pressures which would otherwise be imposed upon the bearing 216 and The electrical and hydraulic system of the machine is illustrated principally in FIGS. and 11. The hydraulic system includes a pump 250 driven by the power plant 62. The pump 250 has a return line 252 and an output or pressure line 254.

A pair of solenoid valves 256 and 258 are mounted on the rear plate 152. A hydraulic line 260 connects the solenoid valves with the pump pressure line 254. The solenoid valve 256 is connected by hydraulic hoses 264 and 266-to the hydraulic cylinder of the hydraulic cylinder member 34. The solenoid valve permits hydraulic fluid flow in either direction through the hoses 264 and 266 so that the piston of the member 34 may move up or down, the control of which is determined by the solenoid valve. Similarly the solenoid valve 258 is coupled by hydraulic hoses 268 and 270 to the hydraulic cylinder of the hydraulic cylinder member 32, the piston movement of which is controlled in the same manner.

The hydraulic cylinders 28 and 30 on the opposite side of the frame are activated through similar solenoid valves 280 and 282. Solenoid valve 282 is connected by hydraulic hoses 284 and 286 to the rear cylinder member 30. Solenoid valve 280 is connected by hydraulic hoses 288 and 290 to the front cylinder member 28.

When the solenoid valves are in the closed or inactive position, hydraulic fluid is cycled between the pump 250 and the hydraulic fluid reservoir 69 via the lines 254, 260, 262 and return line 292. The pump has a built in bypass and the solenoid valves have about a 20 percent leakage, a design parameter of the quick opening function of this particular type of valve.

The hydraulic line 284 forms with hydraulic line260 a hydraulic pressure line loop connected by branch lines to each solenoid valve whereby hydraulic fluid may flow in either direction from the hydraulic hoses through the valvedepending on the setting of the valve.

Referring to FIG. 1 and FIG. 10, the machine has mounted along the side of one of the tracks three stringline followers 300, 302 and 304. These stringline followers are of the same construction as the sensor unit 198 with the exception that the arm' 192 carries a rod which bears against the. stringline as the machine moves forwardly. These types of follower and sensor units are known in the art and are commercially available i I The follower-sensor units 300, 302 and 304 are connected by wires (not shown) to the control unit 68. The solenoid valves 256, 258, 280 and 282 are connected by wires 306, 308, 310 and 312 to the controlunit 68.

An additional control member preferably is included on the machine. lt is a slope .control member 314 mounted on the frame 26. Such slope control member comprises a pendulum or mercury switch connected by wires 316 to the control unit 68. Additionally, the sensor unit 198 is connected by wires 318 (FIG. 8) to the electrical control unit.

The path or direction of forward movement of the machine is controlled by sensor unit 304, the feele r 320 of which bears against the side of the stringline. Each track 22 and 24 is separately driven by its own hydraulic motor. The control unit 68 and follower sensor unit 304.control, in a manner known in the art, the rate of drive and direction of each hydraulic motor for the two tracks and automatically makecorrections in the drive for each track if the sensor feeler 320 moves from its zero position against the stingline, i.e., caused by variation of the path of .direction'of the machine relative to the stringline to the right or left as the machine moves fowardly.

The sensor feelers 322 and 324 of the stringline follower control units 300 and 302 ride against the top or bottom of the string line and are spring loaded thereagainst. When these followers move from zero position, they trigger an electro-hydraulic command via the con trol unit 68 which causes, via the solenoid valves, the hydraulic cylinder members 32 and 34 to be motivated. The sensor unit 302 controls movement of the hydraulic cylinder member 32 in a manner keeping the frame 26 and all members supported thereon at an elevation corresponding to that of the stringline. The sensor unit 300 performs the same function relative to the hydraulic cylinder member 34.

Thus, as viewed in FIGS. 1 and 10, the elevation of the right side of the frame 26 is controlled through the sensor units 300 and 302 and hydraulic cylinder members 34 and 32 in a manner whereby the right side of the frame maintains an elevation corresponding to that of the stringline directly opposite the right side of the frame. Thus, the depth of the concrete and the elevation of its upper surface left behind the machine has a constant, predetermined elevation relative to the stringline.

The left side of the frame has its elevation relative to the stringline controlled via other control members. The slope control member 314 controls, via control unit 68, the hydraulic cylinder 30. This slope control unit is thus settable, or has an auxiliary control on the control unit 68, for presetting a zero slope or inclined slope for the left hand of the frame relative to the righthand side. Assuming a zero slope is set, the slope control member 314 and the auxiliary electrical and hydraulic connections heretofore described, will issue hydraulic fluid flow commands to the cylinder 30 for maintaining the left, rear corner of the frame at the same elevation as the. elevation of the right rear corner of the frame. If the roadway being poured has a crown or pitch, e.g., for water runoff, banking in curves, etc., a setting of the slope control switch provides thespecified crown or pitch for that segment of the roadway being laid.

The hydraulic cylinder member. 28 at the front left corner of the machine is controlled by the torsion bar and its associated mechanism via. the sensor unit 198 and the control unit 68. The objective is to keep the front left comer of the machine at the same elevation as the rear left corner of the frame. If the forward end of the track 22 drops, the frame will twist accordingly. This registers a twist in the torsion bar 160, which in turn causes through the electrical and hydraulic system heretofore described a corrective action by the hydraulic cylinder member 28, Le, a raising of the front lefthand corner of the frame until a frame twist is relieved. Similarly, when the front end of the left track 22 rises, the twist imparted to the frame 26 results in a lowering of the front left comer of the frame 26 by the hydraulic cylinder member 28.

When the front of the right track 24 drops, the right front hydraulic cylinder member 32 raises the right front corner of the frame to maintain it at the stringline-controlled elevation. This registers a twist in the frame 26 similar to that described above when the front of the left track 22 drops. Through the torsion bar control, hydraulic cylinder member 28 raises the left front corner of the frame an amount corresponding to the rise of the right front corner of the frame. As the machine progresses forwardly, the feeler sensor unit 300 will detect a drop in the rear portion of the right track 24 and raise the right rear corner of the frame 26 via hydraulic cylinder member 34 correspondingly. The slope control unit will cause a corresponding rise via hydraulic cylinder member 30 of the left rear corner of the frame.

Through the joint functioning of the hydraulic control cylinders, the righthand side of the frame 26 and also the righthand side of the crown pan remains at a constant vertical-distance below the stringline immediately to the right thereof. The lefthand side of the frame 26 and the crown pan therebetween are also maintained at a constant vertical distance below the horizontal plane of the stringline, which distance may be the same as or different from the righthand side of the frame an'dpan depending on the setting of the slope control unit 314.

When the machine travels over irregular or rough terrain in movement to or from the road bed, between different points along the road bed, etc. it is preferred to deactivate the controls for regulating the movement of the hydraulic cylinder members 30, 32 and 34. Through check valves or other suitable means, these cylinders may be locked hydraulically with the frame preferably half-raised relative to the tracks. The torsion bar-activated control system for the cylinder member 28 remains activated as the machine is driven. It thereby functions continually to relieve twist strain in the frame 26 which would otherwise be imparted thereto as the two tracks traverse theuneven terrain. The machine is even capable of crossing ditches without severe twist strain on the frame 26 by approaching the ditches diagonally or at right angles thereto.

The slip forms for the machine are shown in FIG. 1. They comprise right and left vertical, horizontally elongated, form plates 330 and 332 which are bolted or otherwise fixedly attached to the respective track frames. Forwardly thereof there may be form sections 334 and 336 composed of vertical plates 338 and 340 having rigidly secured thereon bars or plates 342, 344 and 34.6, 348, respectively. These members form a triangular well in which is rotatably journalled a small, pneumatic tire wheel 350 and 352. The wheels keep the front corner of the form sections 334 and 336 slightly elevated relative to the roadway bed and keep the front corner from digging into and binding in the road bed. The form sections 334 and 336 are hinged on shafts 354 and 356 projecting from the track frames so that these sections can be swung upwardly when the machine is travelling in non-paving movements.

The slip form plates 330 and 332 extend rearwardly from the sections 334 and 336 to a point approximating the front edge of the crown pan 150. At this point, two additional form plates, attached to the sides of the pan 150', become the side slip forms. The form plates 330 and 332 preferably overlap the form plates on the pan in a manner precluding escaped concrete between the overlapped portions.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodimentfor the purposeofillustrating the invention; ,1

' The invention-is hereby claimed as followsc' l. A-track drivenmachinecomprising 'a horizontal frameypower driven, endless-track means mounted on respective sides of said frame, mounting" means between respective sides'of said frame and respective track means allowing vertical movement of said frame relative to respective tracks, said mounting means including at least one hydraulic cylinder member connected to a track means and to said frame, hydraulic fluid pump means onsaid machine connected by :hydraulic fluid lines to the'hydrau'lic cylindermember, said hydraulic cylinder member supporting said frame bnthe track means for individually articulated vertical movement of its supported portion of said frame relative to the track means, a torsion bar rigidly connected at o'neend thereof to said frame and adapted to register twisting forces in said frame as ;said machine'moves along terrain, and-hydraulic fluid control means operatively associated with said torsion bar for activating hydraulic movement of said hydraulic cylinder member to raise or-lower said supported ,portionof said frame relative to thetrack means until the torsion bar-registered twist in said.frame-is relieved.

P2; A track driven: machine-as claimedinclaim 1 wherein said mounting means'emboclies four hydraulic cylinder members ,inquadrant arrangement withtwo cylinder members on each side of said frame, said cylinder members supporting the ,weight of said frame .on said track means, first arm means pivotally connected by bearing means to saidsframe and one. Of saiclitrack means, and second arm. means pivotally connectedby J bearing meansto the other track means, said first and secondarrn means coup-ling respective sides of said frame .and respective track means together and allowing, by the pivotal connections of said bearing means,

thevertical movement by said hydraulic cylinder members of said frame relative ,to said track means.

- 3. A-track-driven machine as claimed in claim,2, said bearing meansincluding a bearing on each track means adjacent one of the hydraulic. cylinder members, and

;. each arm means being parallel to its respective side of extending along each side of said frame, first and second, hydraulic cylinder members connected to the first track means and spaced points' on one side of said frame for articulated,'vertical movement of said one side of said frame relative to said first track means, third' and fourth hydraulic cylinder members connected to the second track means and'spaced points on the opposite side of said frame for articulated,"vertical moveme'nt of said opposite'side of said framerelative to'said second track means, hydraulic fluid pump means on said machine connected by hydraulic fluid lines to the respective hydraulic "cylinder members, string-line feeler means'rnount'edbn said machine, firsthydraulic fluid control means operatively associated with said string line feeler means for activating hydraulic moven e'nt'of'said first arid second cylinder members for raising'or lowering said first side ofsaid frame means in a manner maintaining a predetermined alignment with a 'string-liiie'set at predetermined elevations along said road bed, a tor'sion'barrigidly connected atone end thereof to saidframe means adjacent said opposite side thereof and adapted to register twisting forces in said frameas said machine moves along the roadbed, second hydraulic fluid control means'operatively associder member t6 maintain said opposite side of said frame means at a predetermined first side of said frame.

' 5. A paving machine as claimed in claim" 4, a crown level relative to said pan beneath and supported by said' 'frarn'for shaping the uppe'r surface of the'c'oncreteat the designed elevation and configuration, and vertical, slip form plates mounted on said machine adjacent to respective track means for restraining and shaping the side edges 'of the concrete strip. i i

6. A'paving machine as claimed i'n claim 4, a first arm parallel to said first track means and pivotally connected at one end of said arm to said frame and at the other end to said first track means, and asecond arm parallel to said second track means and pivotally connected at one end "of said second arm to said frame and at the other endlt'o said second track means. I 

1. A track driven machine comprising a horizontal frame, power driven, endless track means mounted on respective sides of said frame, mounting means between respective sides of said frame and respective track means allowing vertical movement of said frame relative to respective tracks, said mounting means including at least one hydraulic cylinder member connected to a track means and to said frame, hydraulic fluid pump means on said machine connected by hydraulic fluid lines to the hydraulic cylinder member, said hydraulic cylinder member supporting said frame on the track means for individually articulated, vertical movement of its supported portion of said frame relative to the track means, a torsion bar rigidly connected at one end thereof to said frame and adapted to register twisting forces in said frame as said machine moves along terrain, and hydraulic fluid control means operatively associated with said torsion bar for activating hydraulic movement of said hydraulic cylinder member to raise or lower said supported portion of said frame relative to the track means until the torsion bar-registered twist in said frame is relieved.
 2. A track driven machine as claimed in claim 1 wherein said mounting means embodies four hydraulic cylinder members in quadrant arrangement with two cylinder members on each side of said frame, said cylinder members supporting the weight of said frame on said track means, first arm means pivotally connected by bearing means to said frame and one of said track means, and second arm means pivotally connected by bearing means to the other track means, said first and second arm means coupling respective sides of said frame and respective track means together and allowing, by the pivotal connections of said bearing means, the vertical movement by said hydraulic cylinder members of said frame relative to said track means.
 3. A track-driven machine as claimed in claim 2, said bearing means including a bearing on each track means adjacent one of the hydraulic cylinder members, and each arm means being parallel to its respective side of the frame.
 4. A road paving machine comprising a horizontal frame, means on said frame for spreading and laying a strip of road paving material on a roadbed surface as said machine moves forwardly along the roadbed, first and second track means each having an endless track extending along each side of said frame, first and second, hydraulic cylinder members connected to the first track means and spaced points on one side of said frame for articulated, vertical movement of said one side of said frame relative to said first track means, third and fourth hydraulic cylinder members connected to the second track means and spaced points on the opposite side of said frame for articulated, vertical movement of said opposite side of said frame relative to said second track means, hydraulic fluid pump means on said machine connected by hydraulic fluid lines to the respective hydraulic cylinder members, string-line feeler means mounted on said machine, first hydraulic fluid control means operatively associated with said string line feeler means for activating hydraulic movement of said first and second cylinder members for raising or lowering said first side of said frame means in a manner maintaining a predetermined alignment with a string-line set at predetermined elevations along said road bed, a torsion bar rigidly connected at one end thereof to said frame means adjacent said opposite side thereof and adapted to register twisting forces in said frame as said machine moves along the roadbed, second hydraulic fluid control means operatively associated with said torsion bar for activating hydraulic movement of the third hydraulic cylinder member to raise or lower said opposite side of said frame relative to said track means until the torsion bar-registered twist in said frame is relieved, and slope control means operatively associated with said fourth hydraulic cylinder member to maintain said opposite side of said frame means at a predetermined level relative to said first side of said frame.
 5. A paving machine as claimed in claim 4, a crown pan beneath and supported by said frame for shaping the upper surface of the concrete at the designed elevation and configuration, and vertical, slip form plates mounted on said machine adjacent to respective track means for restraining and shaping the side edges of the concrete strip.
 6. A pavIng machine as claimed in claim 4, a first arm parallel to said first track means and pivotally connected at one end of said arm to said frame and at the other end to said first track means, and a second arm parallel to said second track means and pivotally connected at one end of said second arm to said frame and at the other end to said second track means. 